1. Field of the Disclosure
The field of the disclosure relates generally to optical fibers, and more specifically to a system for removing a polymer coating overlaying a glass optical fiber, such as during preparation of the optical fiber for attachment of a connector to the optical fiber.
2. Technical Background
Benefits of optical fibers include extremely wide bandwidth and low noise operation. In cases where high bandwidth is required between two interconnection locations, fiber optic cables having fiber optic connectors may be used to communicate information between these locations. The fiber optic connectors also may be used to conveniently connect and disconnect the fiber optic cables from the interconnection locations when maintenance and upgrades occur.
Each of the fiber optic connectors may include a ferrule assembly having a ferrule. The ferrule has several purposes. The ferrule includes an internal pathway, called a ferrule bore, through which an optical fiber is supported and protected. The ferrule bore also includes an opening at an end face of the ferrule. The opening is where an optical surface of an end portion of the optical fiber may be located to be aligned to an end portion of another optical fiber of a complementary connector. The end portions of the optical fibers need to be precisely aligned to establish an optical connection so that the optical cores of the optical fibers may communicate.
The optical fibers typically include a glass fiber (e.g., cladding and core) surrounded by a protective polymer coating which for several reasons is removed from the glass fiber prior to being disposed within the ferrule. One reason is that the polymer coatings do not currently have the robust mechanical properties necessary to be attached to the ferrule bore to withstand the cyclical tension experienced during the use of the fiber optic optic connector over time without displacement creep or breakage. Another reason is that the optical fiber is not centered within the polymer coating with sufficient accuracy to permit the glass fiber to be precisely located within the ferrule bore without removing the coating.
Various methods are available to remove the polymer coating from an end portion of the optical fiber: hot gas stripping, mechanical stripping, chemical stripping, and laser stripping. All of these methods have drawbacks. Hot-gas stripping uses a heated jet of gas (e.g., nitrogen or air) to melt and remove the coating, but often considerable debris is created. The hot-gas stripping approach may also incompletely evaporate the polymer coating, and/or may overheat heat-sensitive materials in close proximity to the fiber core.
Mechanical stripping of optical fibers includes physically removing the polymer coating material from the glass fiber with a semi-sharp edge of a stripping blade made of a metal or a polymer, as may be similar to mechanical stripping of electrical wires. However, mechanical stripping may have issues because the optical fiber may be damaged and extensive consumables (e.g., stripping blades) are needed that require time-consuming procedures to inspect and replace consumables as needed in an operations environment. Chemical stripping of optical fibers uses chemicals to dissolve the polymer coating from the glass portion of the optical fiber, but these chemicals require extensive procedures to protect the environment and safety measures to protect personnel.
Laser stripping utilizes one or more laser beams to strip the polymer coatings from glass optical fibers using a vaporization or ablation process. As is depicted in FIG. 1, laser stripping may include a laser beam 10 to ablate a coating 12 from a glass portion 14 of an optical fiber 16 prior to laser cleaving. The laser beam 10 may be incident on the optical fiber directly or may be focused upon the optical fiber 16 with a complex reflector 18. However, conventional laser stripping techniques may have issues such as weakening optical fibers so that they have difficulty withstanding tensile forces experienced when used with fiber optic connectors. Moreover, conventional laser techniques may also be too slow requiring physical movement of the optical fiber relative to the laser. Conventional laser stripping techniques also may not fully remove the coating from the optical fiber, and so inadequately stripped coating portions may obstruct the optical fiber from being inserted through a ferrule of a fiber optic connector. Further, conventional laser processing equipment also has a large footprint and, in combination with laser cleaving machines, occupy large areas of expensive manufacturing space.
What is desired is a coating removal system and process which preserves the tensile strength of the optical fiber, meaning the ultimate strength or maximum tensile stress prior to failure, such as fracture, of the optical fiber. The system and process should uniformly remove the coating from the optical fiber while minimizing the risk of damage to the optical fiber. The system and method should not require extensive consumables or chemicals, and should not have a large manufacturing footprint.